The application and use of the essentially ubiquitous one-dimensional bar code are well established. Such bar code symbols are provided as images having two physical dimensions, however the bar code includes information coded in only one dimension (e.g., left to right). While such one-dimensional bar codes have found innumerable applications, their usefulness is ultimately limited by amount of information which can be encoded in each such bar code.
Two-dimensional bar codes, enabling encoding of greatly increased quantities of information, have now been proposed. FIG. 1 shows an example of a two-dimensional bar code. Such bar codes typically include a few to many rows of coded data grouped in parallel alignment between start and stop patterns which bound the group of rows of coded data transversely to the rows. Coded row data, also typically included in the bar code, may provide information identifying and distinguishing individual rows of data, information regarding the data coded in such a row, information enabling error correction, etc. While such two-dimensional bar code images also have two dimensions, they differ from one-dimensional bar codes in providing two-dimensions of coded information. An example of a two-dimensional bar code is given in the present inventor's prior U.S. Pat. No. 5,113,455, entitled "System For Encoding Data in Machine Readable Graphic Form", issued May 12, 1992. Another example, described as the "PDF417" symbol, has been proposed in a PDF417 Specification, dated October 18, prepared by the present inventor for Symbol Technologies, Inc. and submitted for review by the Technical Symbology Committee of the Automatic Identification Manufacturers, Inc.
One-dimensional bar codes have come into wide usage on the basis of permitting application to supermarket items, vehicles, inventory parts, etc., of an image representing a multi-digit identifying number which is readily machine-readable. A variety of devices and applications of technology using lasers or charge coupled devices, for example, have been made available and are in wide use for reading such bar codes. On the one hand, two-dimensional bar codes make possible a wide-variety of new uses and applications in which a much wider range of information and data may be encoded and distributed by mail, facsimile transmission, etc., alone or in combination with other graphic or textural images, as well as being affixed to products, vehicles and inventory items, for example. On the other hand, two-dimensional bar codes require more complex capabilities for accurately reading the greatly increased amount of encoded data. Actual location and orientation of the bar code image within the scanned image (assuming the scanning device, as a practical matter, actually scans a somewhat larger image area which includes at least one bar code image) may entail a substantial data processing capability.
The result of the foregoing is that extension of use of two-dimensional bar codes to all logical applications may be restricted on an economic basis in the absence of efficient and economical methods and arrangements capable of implementing the required scanning and decoding of the bar code images, including methods and arrangements for locating and determining the bounds and orientation of two-dimensional bar code images within scanned image areas in order to enable such decoding of the bar codes.
It is therefore an object of this invention to provide methods and systems capable of both locating and determining the bounds and orientation of two-dimensional bar code images within a scanned image area.
Additional objects are to provide new and improved methods and systems for locating bar code images and particularly such methods and systems for providing bounding coordinates of a bar code included in scanned image data.